Thermoelectric heat pumping apparatus



Dec. 2, 1969 c. J. MoLE ETAL Re. 26,728

THERMOELECTRIC HEAT PUMPING APPARATUS Original Filed Oct. 30. 1963 6Sheets-Sheet 1 N 3 2' NH 5 1-*8 2 83 2 S 2 g f a 3 'i 3 s e 8 :f: s V f:2

i3 N E u' V/ IL a' Q Y N o Y- 3 f@ 2! V Q *e I S 82 N 2 g s n E C i u HE S D 3 3 .J kl O s E p- E 1 l L 1 l Q O O C O O 0 O o n l0 N anon usdsnm oadwnd man WITNEssEs cluvileudrt'sl v 9,/ ec o e M "j/ aewmi M.wepfer Dec. 2. 1969 C, J. MQLE ETAL n Re. 26,728

THEHMOELECTRIC HEAT PUMPING APPARATUS original Fixed oct. so. 1963 ssheets-sheet z THERMOELECTRIC COOLING EFFECT OF THERMAL RESISTANCE 66 ONPREFORMANOE lllnunl DIRECT TRANSFER WORKING POINT l l l Illlll o l s*HEAT PUHPED PER POUND OF THERMOELECTRIC MATERIAL BTUI'RrLB 5o ,.0 lo2coNvENTlouAL svsvEM j wonums PomT 1 l 1 l :o .so .25 .2o .1s :o .os o

PELLET LENGTH PER um? AREA (L1A Dec. 2, 1969 C, J, MQLE ETALTHERMOELECTRIC HEAT PUMPING APPARATUS 6 Sheets-Sheet 3 Grgnal Filed Oct.30. 1963 O E BNOH 83d 9,018

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Dec. 2, 1969 C. J. MOLE ET AL THERMOELECTIC HEAT PUMPING APPARATUS 6Sheets-Sheet 4 Original Filed Oct. 3D. 1963 Dec. 2, 1969 c. J. MousETAI.

THERMOELECTRIC HEAT PUMPING APPARATUS 6 Sheets-Sheet 6 Original FiledOCI.. 30, 1963 HEATED FLUID FLOW CIRCUIT COOLED FLUID FLOW CIRCUITUnited States Patent Oce U.s. ci. sz-s 14 claims Matter enclosed inheavy brackets I] lp rs in the original patent but forms no part of thisre specilicatlon; matter printed in italics indicates the additions madeby reissue.

Our invention is directed generally to thermoelectric assemblies andmore particularly to arrangements of thermoelectric elements in heatexchange relationship with lluids to provide maximum performance in thecooling of such fluids for air conditioning or refrigerationapplications or in warming such lluids for heating purposes. Thisinvention is also directed to a thermoelectric arrangement whichoperates as an electrical generator.

Thermoelectric apparatus have been constructed in the past for impartingheat and/or cold to fluids, however, the heat removal or absorbingcapacity of such prior art apparatus when compared to the relativelyexpensive thermoelectric materials which must be utilized with suchprior art arrangements causes the cost thereof to be prohibitive.

The present invention, as will be explained in detail hereinafter,overcomes the deficiencies of the prior art and results in novelstructures where heat addition and/or removal capacities of suchapparatus are increased substantially, while, at the same time, theamount of thermoelectric material utilized is substantially reduced. inaccordance with this invention, a heat flow path in adjacent stacks ofthermoelectric devices is provided from the thermoelectric material tothe heat transfer fluid in a manner eliminating electrical insulation, amajor contribution to thermal resistance, from the heat ow path. Thisarrangement provides electrical insulation between adjacent current flowpaths in the thermoelectrc structure to prevent short-circuiting ofcurrent llow which would result in the bypassing of certain of thethermoelectric junctions.

Accordingly, it is an object of this invention to provide a novel andefficient thermoelectric heat producing and removing arrangement whichminimizes the amount of thermoelectric material required to attain apredetermined heating and/or cooling capacity.

Another object of this invention is to provide a novel and efficientthermoelectric arrangement for the generation of electricity.

A further object of this invention is to provide a novel and efficientthermopile having a plurality of thermocouple junctions and a heatexchange uid flowing thereadjacent wherein a heat tlow path between thejunctions and the uid is formed with no electrical or thermal insulationtherein.

A further object of this invention is to provide a novel and eticientthermopile having a plurality of serially connected adjacent stacks eachforming a current and heat How path and having electrical insulationdisposed only between such stacks.

A further object of this invention is to provide a novel and etlicientthermopile having a plurality of serially connected adjacent stacks eachforming a current and heut flow path and having electrical insulationdisposed between such stacks but having no electrical insulation in theheat ow path between the thermoelectric junctions und a heat exchangefluid.

Another object is to provide a novel thermoelectric retil) asuma z, tsssfrigeration apparatus of compact sine, low cost and ot high etliciency.

Further objects and advantages of our invention and features of noveltywhich characterize the invention will be pointed out in pasticularity inthe claims annexed to and forming a part of this specification. x

For a better understanding of our invention. reference may be had to theaccompanying drawings. in which:

FIGURE l is a graphical illustration analyzing the operation of athermoelectric construction formed pursuant to the principles of thisinvention:

FIG. 2 is another graphical illustration showing the e'ect oi thermalresistance on the performance of a ther moelectric construction:

FIG. 3 is a graphical illustration similar to FIG. l for thermoelectricelements of smaller length than those utilized in FIG. l; i

FIG. 4 is a schematic view of a thermoelectric system in whichembodiments of the present invention may be utilized;

FIG. 5 is a composite view having portions thereof broken away andhaving portions in section illustrating a specilic embodiment of thisinvention;

FlG. 6 is a side elevation view. partially in section. of a couplingelement utilized in the arrangement illustrated in FIG. 5: and

FIG. 7 is a perspective view of another embodiment of this invention;

FIG. 8 is a schematic view of the thermopile ol' FIG. 5 illustrating theheated lluid ow circuit thereof:

FIG. 9 is a view similar to FlG. 8 illustrating the cooled lluid llowcircuit of the thermopile of FIG. S:

FlG. l0 is a fragmentary composite view of the apparatus of FIG. 5 andillustrating a modication.

THEORY OF APPROACH Considering the problem of thermoelcctric heating orcooling and from the standpoint of the equations which. according to ourpresent understanding of the art. govern the performance thereof. athermopile for providing cooling having ultimate utility in the area ofair conditioning or refrigeration will be analyzed in detail. From timeto time as this analysis proceeds, ultimate conclusions will be pointedout in particularity.

According to our understanding of the phenomenon of thermoelectriccooling. the basic equation governing the pumping ot heat bythermoelectric devices is:

where Q=heat pumped; B.t.u./hr.

I=current: amperes a=thermoelectric power; n voltsl F.

te=absolute cold junction temperature: F.

R=electrical resistance across thermoelcctric pellet: ohms K=thermalconductivity oi thermoelectric pellet: B.t.u./

At=temp. difference between pellet hot and cold junctions; F.

Considering Equation l, it will be noted that the quantity uit, shouldbe maximized in value as it maken a positive contribution to the amountof heat pumped. Simi. larly, since the quantities VzIR and Kat detractfrom the amount ot heat pumped, these quantities should be minimized.Furthermore. it must he realized that certain of the above quantitiesare interrelated so that an attempt to maximize n positivelycontributing quantity may well increase the ellect of a negativelycontributing quantity to a degree greater than the positive contributim.

More specifically in FIG. l there is illustrated the oomponentquantities of Equation 1. lt is to be realized that for anythermoelectrie apparatus a Coellleient ot lierforinancelI` (COP) must bechosen for the purpose of setting the desired `operating efficiencies ofthe apparatus.

The Coecient of Performance is defined as:

Heat pumped z Q Input power required to pump heal'. 12R-fallita,

InFlG. l, 'the current flowing through a thermoelectric device havinga"pellet length of 0.25 ii1.a`nd`having no thermal resistance in theheat o`w` path'is` plotted on the horizontal axis or abscissa and theheat pumped therethrough is plottedn on' 1the vertical axisi or'ordinate l2. With ,theseucoordinates the quantity alt is depicted bythe'curve 14; the quantity Kati,V fot" At".- l0 F. is depicted Jby thecurve 16', the quantity Kdtp-i-l/:PR for various values ofd'tp aredepicted by set of ycurves 1B; and the riu'antit'y1 of COP=l is plottedby the curve 20. At points 2,2, 24, 26, 28. 30, 32 and 34 where theCOP=l curve intersects the KAtp-t-ilk curves 18, the vertical distancebetween such points and the curve 14. `is set forth by the line 36, 38,40, 42, 44, 46, and 48. The length of, `each of the lines 36,` 3B, 40,42, 44, 46 and 48 depicts the quantity Q lor a thermoelectric devicedesigned to operate aty a, predetermined current tlow therethrough andat predetermined temperature difference across the pellet (Atp). Theresults of FIG. l analysis is set forth bythe following table.

TABLE t Thermoelectric operation Conditions; liet length=0.25 ln.,pellet area=1 in); pellet compostl tion=htsmiiieh tellurtde. COP-'1; nothema! instalation ln heat Ilow path. Figure o( mertt=2.5) ltH/ C.)

COP=

Current (amps) y At, F.) Q (ll.t).u.l lolnt 70 13 2 60 18 24 50 22 402li. 3 28 Il) ZL 5 30 20 3l s 32 l0 34 34 p= pellet resistivity L=pelletlength A=pellet area It will therefore be seen thaty the pellet lengthshould he minimized to decrease thetpellet resistance and similarly thepellet area should be maximized to anoptimum ratio of pellet length topellet area.

lt-has been determined that for a given temperature difference betweenthe heat source and the heat sink and for a given thermal resistance inthe heat flow path and for a given figure. of merit (a2/pl() for thethermoelectric system together with a given COP, an optimum ratiohofpellet length to pellet area (L/A) can be determined. lt is to berealized that while it is an objective of this invention to removethermal resistance from the heat ow path in the thermoelectricV system,even the best heat conductors, such as silver, copper and aluminum, haveassociated with them some thermal resistance (usually of very lowmagnitude). Thus, it must be taken into consideration that while shorterpellets of larger areas will increase the heat produced, the problem isone 0f Pumlins le het* ihmuh Pellet t9 lhs heat Sink and.

hence an optimum ratio of pellet length to pellet area can be achieved.Thus, an objective is to provide an optimum pellet length to pellet arearatio for a given thermoelectric arrangement. Furthermore, since thecost of thermoelectric material is a major factor in the cost of athermopile, it is to be realized that the construction of a choice ofoptimized pellet length to pellet area ratio will result in asubstantially less expensive yet more etlicient thermopile per unit areaby virtue of the reduction of the total amount of thermoelectricmaterial used.

As pointed out above, the quantity KAtp detracts from the amount of heatpumped (Q). ln all arrangements of the prior art of which we are aware.there are large thermal resistances in the heat ow path which tend toenlarge the quantity KMP, inter alia, as follows:

ln the quantity KAtv, the quantity K is substantially constant, and thequantity AtD varies pursuant to `the following equation:

where At=temperature difference betwen heat source and heat For anygiven condition of temperature difference between the heat source andheat sink, the heat pumping rate depends upon the thennal resistances inthe heat flow path. However, in accordance with this invention,apparatus are provided wherein At", and Atlle are specifically made toapproach zero since the principal thermal resistances, located betweenthe pellet and the heat source and between the pellet and the heat sink,are substantially eliminated. Thus the quantities At", and ttm which actto enlarge the quantity Atn, approach zero. Accordingly, for structurespursuant to this invention, Equation 4 approaches the ideal case where:

Airat (5) Thus, it may also be concluded from this analysis that thermalresistances in the heat tlow paths must be kept at the lowest levelspossible.

The main source of thermal rcsistances in conventional systems iselectrical insulation which separates adjacent stages of the thermopile.With prior structures, electrical insulation was necessary between theheat source, the heat sink and the thermoelectric pellets. The thicknessof such insulation depended upon the test voltage of such devices.Obviously, the higher the voltage, the more difficult the heat transferproblems with such systems becomes. For production apparatus of wideutility, the test voltage would be required to meet a level up to 2000volts, to satisfy NEMA standards for safety. To achieve such voltagesand retain adequate thermal performance, electrical insulation in theheat Iiow path must be removed. Devices pursuant to this inventionwherein the thermal and electrical resistances in the heat llow pathhave been removed and termed herein as direct transfer" devices.

A comparison of the operating levels :ind capabilities of directtransfer" devices versus conventional devices having thermal insulationin the heat tlow paths thereof is illustrated graphically in FIG. 2 ofthe accompanying drawings. ln FIG. 2, there is plotted on the ubscissa.the length to area ratio of the pellet on a linear scale while on theordinate, on a logarithmic scale there is plotted the heat pumped perpound of thermoelectric material (B.t.u./hr.lb.). Each curve illustratedin FlG. 2 depicts the characteristic of a thermoelectric element for agiven quantity of thermal resistance in each heat tlow path between theheat source and the heat sink. 'l he curves of FIG. 2 are identifiedrespectively by the reference characters 50, 52, 54, 56, 58, 60, 62, 64and 66 and the characteristics of cach curve are identified by thefollowing table:

TABLE II [Effect nl thermal resistance on performance conditions.Temperature dinan-nce lmtween heat source nml heat slnk (at.) F., U0 l=unit.y; Fig. of merit nl system (a2/pK)v.:2.5x10-l/ C.)

Thermal (invth No. ltrststnntxe lli-at. pumpml per lh. nl nuuurlul ll-.llt.l.u.hr.) nl. pvllvt length tn pollaiuwu ruliu 52. 0..| 170ll.t.u./Ili.,'hr. at .20 lu. per

unit aren.

66 0. 25 2,l50 ll.t.u./ll)./lir. ai .05 lu. per

unil. area.

58 0. l0 3,180 I\.t.u./lb.flu. at .05 ln. per

unlt area.

00. 0.1.5 4.650 ll.t.u./lb./hr. at .06 ln. per

unit area.

62 0.10 6,600 B.t..u./lb.lhr. at. .05 in. per

unlt. area.

64 0.06 7,950 B.t.u./lb.[hr. at .05 ln. per

unit area.

66 0.00 10.800 B.t.u./lb.lhr. at .05 in. per

t unit area.

Thus it can be seen from Table Il that by decreasing the thermalresistance in the heat flow path, the amount of heat pumped per pound ofmaterial used increases substantially exponentially with a decrease inthe thermal rcsistance. Viewing curves 50 and 52 wherein substantialthermal resistances exist. it should be noted that performance increasesup to a pellet length of 0.20 in. but that as pellet length is furtherdecreased, the performance `falls olf rapidly. For "direct transfer"systems, the minimum length to area ratio can be decreased to a rangebetween 0.05 and 0.02 inch per unit area. lt is to be realized of coursethat curve 66 of FIG. 2 which depicts zero thermal resistance is merelya theoretical calcula. tion, as structures having no thermal resistancecannot in practice be achieved. Furthermore, it must be realized thatfor very small pellet lengths a substantial amount of heat is generatedbut that it is impossible to remove or pump all of the generated heattherefrom to the heat sink. Thus an optimum pellet thickness must bechosen with consideration given to the heat removal capabilities of thesystem construction. For example, in FIG. 2, the point 68 on curve 52depicts the operating level of systems forming the prior art. At point68. 170 B.t.u./ hr.lb. would be generated. By reducing the thermalrcsistance in the system and by decreasing the pellet thick- Vness to avalue wherein the system is capable of trans' porting or pumpingsubstantially all of the heat generated to the heat sink, substantiallymore heat can be pumped pursuant to the teachings of this invention.More specifically, at point 70 on curve 62, 6600 B.t.u./hr./lb. can bepumped for a pellet length of 0.05 in. per unit arca `and a thermalresistance of 0.10 F./B.t.u.hr.

Once a direct transfer" system is achieved wherein thermal resistancesare substantially reduced, it is desirable to determine what the effectof higher operating currents for the thermopile will achieve. Sincepellet length decreased, the system resistance is decreased and highercurrents result. It must be remembered that in systems utilizingelectrical insulation in the heat flow paths the increasing of theapplied test voltages necessary Vfor safety and reliability tests (NEMAStandards) would require an increase in the size of the electricalinsulation, thereby resulting in an increase in the thermal resistancein the heat ow path. Accordingly, the following analysis is made only inconjunction with a system having no electrical insulation (thermalresistance) in the heat flow path. Concurrently with increased currents,the pellet length is made one-fifth the size of the pellets depicted inFIG. l.

FIG. 3 is a graph similar to FIG. l showing a family of curves for apellet length per unit area of one-fifth Thcrmoelectric operationitomlltlu'is: pnllvt. length 4000 ln.; |wll|t urmifl luJ; pnlltil.curnnnslllnn Lililitnulith batlurltlu; CUP-1; un thmmul lnsuluttun luheat. lluw putti ,Inutili Current (Amps) Atpt" F.) L Q(:l.t).u./ l'ulnt00 l 83 2l' 50 100 Ztl 40 124 '2B' 30 140 30' 20 154 32' l0 109 M'Comparing Table II with Table I, it will be seen that substantiallyhigher heat pumping rates (Q) can beV obtained by increasing the currentow through the System when the pellet length per unit area is decreased.

Based upon the above analysis of our present understanding of theoperation of thermopilcs, reference is now made to FIGS. 4 to l0 whichdepict specific embodiments of direct transfer" thermoelectric systemswhich utilize to advantage the above-described requirements for anelcient, high output thermopilc.

More specifically, in FIG. 4 there is illustrated in schematic form theoperation of a thcrmopile wherein the cooled fluid is in liquid form andthe cooling fluid is also in liquid form. A direct transfer thermopileis denoted generally by the reference character 1l and will be describedin more detail as this specification proceeds. The thermopile l1 isprovided with a pair of terminals which are formed to he energized bydirect current power passing from a power source I3 to theaforementioned terminals by conductors l5. In the event the power sourceI3 is of the alternating current type, as illustrated in FIG. 4, thereis interposed between the power source 13 and the conductors l5 arectifying means 17 which serves to convert the alternating potential toa direct current potential. ln a liquid-to-liquid thermopile arrangementthere is provided a flow circuit for the heated fluid, denoted generallyby the reference character 19, and a flow circuit 2l for the cooledfluid. The heated fluid ovv circuit 19 includes flow conduits 23 and 25which are desirably connected to an internal flow circuit for heated uidlocated within the thermopile l1. Flow circuit 19 also includes a heatexchange means. for example the heat exchanger 27 illustrated herein as:t liquid'to-liquid type, and the conduits 23 and 15 are connected to acoiled heat exchange conduit 29. to form a recycling flow path. In theheat exchanger 27 thc primary circuit is formed by the coiled tube 29,and :i secondary circuit, formed by the outer casing of the heatexchanger 27 and includes an inlet conduit 3l and an outlet conduit 33respectively communicating with the interior of the heat exchanger 27.As is apparent from FIG. 4. the primary circuit and secondary circuit ofthe heat exchanger 27 are disposed in heat exchange relati0nship. Asheated uid passes through the coil 29. such heated fluid is disposed inheat exchange relationship with secondary system fluid passing into theheat exchanger 27 through conduit 3l resulting in the heating of thesecondary system fluid by the primary systelm fluid, and concurrentlyresulting in the cooling of the primary system fluid.

Similarly, the flow circuit 2l for the thcrmopile cooled fluid isprovided with a heat exchanging means 35, illustrated in the example ofFIG. 4 as a liquid-to-air heat exchanger. More specifically, the heatexchanger 35 is provided with a pair of spaced headers 37 and 39 theinteriors of which are connected together by a plurality of heatexchange tubes 4l. The tubes 4l desirably are spaced to permit the flowof air past the tubes 4l to cause cooling of the air. The ow of air pastthe tubes 41 is aided by suitable air circulating means such as a fan43. The cooled fluid flow circuit 2l desirably is provided with a pairof conduits 4S and 47 and the conduits 45 and 47 are dcsirably connectedto an internal cooled fluid ow circuit formed within the thermopile ll.The conduits 45 and 47 are also respectively connected to the headers 37and 39 to form the closed recycling heat exchange loop 2l.

From a thermodynamic standpoint, cach of the recycling flow loops I9 and2l is provided with a heat source and a heat sink. In the heated fluidllow circuit I9, the heat source comprises the thermopile ll and theheat sink is formed by the heat exchanger 27. In the cooled Huid flowcircuit 2l, the heat sink is formed by the thermopile l1 and the heatsource is formed by the heat exchanger 35. It will, therefore, berealized that the thermopile 1l forms both a heat source and a heat sinkand, therefore, includes two independent ow circuits therein, one forthe heated lluid and one for the cooled fluid.

A specific example of a direct transfer thermopile ll is illustrated inFIG. 5. The thermopile Il of FIG. 5 is formed by a plurality of rows ofelectrically conductive Iand thermally conductive blocks 5l. desirablyformed from a material having very low resistance to the llow of currentand having excellent heat transfer properties, for example, copper oraluminum.

For the purpose of referring to the rows of blocks 5l in FIG. 5, each ofthe front rows, of which six are illustrated. is denoted by thereference characters l. 2, 3, 4, 5 and 6, respectively. Each of the siderows of blocks 5l. going from front to the back of the thermopile ll isdenoted by the reference characters A, B. C, D, E and F, respectively,six of which are illustrated in FIG. 5. Similarly, each of blocks 5Iforming a given row, moving from the bottom block in a thermopile row tothe top block in a thermopile row is denoted by the reference charactersA, B, C. D and E, respectively. Thus, to refer to any given block 5l inthe thermopile ll, for example, the block denoted by the referencecharacter 50', such block may be identified by a combination of theaforementioned reference characters. Thus, the block S1' can also bereferred to as the block 6Ec.

In accordance with the invention there is disposed `intermediate eachpair of vertically adjacent blocks 5l.

a quantity of thermoelectric material 53 of a suitable composition suchas bismuth telluride. The thermoelectric material S3 is illustrated inthis example as nine pellets 55 mounted on the confronting horizonalsurfaces of the adjacent blocks Sl. Each of the pellets 55 is formed tohave a predetermined pellet length (the length of the material in thevertical direction the direction of current flow therethrough) forexample 0.05 inch. Each of the pellets 55 may be fabricated by processesknown in the art and each pellet 5S desirably is metallurgically bondedto the contiguous blocks 5I by suitable means` such as by soldering. Thebonding procedure desirably provides a low resistance joint between thepellet 55 and the contiguous blocks Sl. Each of the blocks 5l desirablyincludes a transverse opening r flow path 57 therethrough to permit thepassage of a heat transfer fluid. Fach of the flow openings 57 is formedintegrally in the blocks l by suitable means, such as by a boringoperation. and the opening 57 in each of the horirontally disposed rowsof blocks extending from the front side of the thermopile to the back,is desirably disposed in aligni ment with one another to provide acontinuous how path therethrough. For example, the llow openings S7 ineach of the blocks Ac, 68e. 6Cc, 6Dc. 6F.c and 6Fc form a nntinupus flowpath through the device. Each of the end blocks 5l forming the front andrear surfaces of the thermopile ll, for example the blocks 5l and rows1A, 2A, 3A, 4A, 5A and 6A and in 1F, 2F, 3F, 4F, 5F, 6F is provided witha tubular extension 59 (illustrated in FIG. 5 only in the front portionof the thermopile 10) which desirably is formed integrally of the blocks5l and is disposed respectively in alignment with the adjacent tlowpaths S7. The extensions 59 are formed to receive tubular conduits 6lwhich interconnect predetermined ow paths 57 to form a pair of separateflow circuits through the thermopile, such that each block 5l contprisesa segment of one of the flow paths. As will be described in FIGS. 8 and9, the heated uid (tluid to be warmed by the thermoelectric action),passes through one of the separate internal flow paths while the cooledtluid passes through the other internal llow path. Each set of blocksforming a given vertical level comprises a portion of the same ow path.For example, those blocks 5l in the upper horizontal row of blocks, atlevel e, form the llow path for heated fluid. The next lower level ofblocks, or level d, form a portion of the ow path for cooled fluid.Similarly, the horizontal rows of blocks, at levels a and c, form aportion ot the Bow path for heated lluid, and the rows of blocks atlevel b complete the How path for the cooled fluid.

Considering now the heated fluid ow path for the thermopile ll. it willbe noted that an inlet conduit 63 is mounted on the tubulation 59 on theblock JAe. An exit conduit 65 for the heated tluid flow path issimilarly secured to the tubulation S9 on the block 4Ae.

The flow circuit for the heated tluid is illustrated schematically inFIG. 8. In referring to FIG. 8 solid lines connecting channels or flowpaths 57 depict a tubular connection between the flow paths 57 disposedon the front surface of the thermopile 11, for example the tube 67.Connections between the flow paths S7 made at the rear of the thermopileare illustrated in FIG. 8 by dotted lines. The heated lluid flow circuitenters the thermopile l1 through the inlet 63 in horizontal row 3e. Arear connection of row 3e and row 1c is made so that fluid llows fromrow 3e to the blocks in the row le. The fluid then passes through row laby means of a connection made in the front of the thermopile ll. Fromrow la, tluid passes to row 2a through a rear connection. The fluid thenpasses from row 2a to row le through a front connection and therefrom bya rear connection through row 2e. From row 2e, a front connection 67 ismade to row 2c and fluid passes from row 2c to row 3c through a rearconnection. A front connection is made between row 3c and row 3a andfluid passes from row 3a to row 6a through a rear connection. From row6a the fluid passes through a front connection through row 6c andtherefrom through a rear connection through row 6e. The flow path forheated uid continues from row 6e through a front connection to row 5aand therefrom through a rear connection to row 4a. From row 4a, a frontconnection is made to row 4c and therefrom, by means of a rearconnection. to row 5c. A front connection is formed between rows Sc and5e to cause lluid to ow therethrough and lluid passes from row 5e to arear connection through row 4e. The outlet conduit 65 is connected tothe front tabulation ot' the block 4Ae. so that fluid exits from theheated lluid liow circuit of the thermopile ll from horizontal row 4e.

Similarly. in FIG. 9. there is illustrated schematically the internalcooled Huid flow circuit. The cooled fluid llow circuit of thethermopile t0 includes an inlet conduit 69 connected to the tuhulationS9 of the bloeit BAd and an outlet conduit 7l is connected to thetubulation 59 of the block 4Ad. Fluid enters the cooled fluid flowcircuit through the inlet conduit 69 and passes through the flow path 57formed in horizontally extending row 3d. A rear connection is madebetween row 3d and row 2d to cause uid to flow through the row 2d. Fromrow 2d, ttuid passes through the passageway 51 in row la by means of afront connection and from row ld through row lb by means ol a rearconnection between rows ld and lb. A front connection is made betweenrows lb and 2b to cause fluid to flow through row 2b and therefrom torow 3b by means of a rear connection. From row 3b a front connection ismade to row 4b and from the latter row to `row 5b by means of a rearconnection. Fluid then passes from row 5b to row 6b by means of a frontconnection and then through a rear connection made between rows 6b and6d to cause lluid then to flow through row 6d. The cooled tluid ow pathcontinues from row 6d to row 5d bymeans of a iront connection andtherefrom to row 4d by means of a rear connection. From row 4d, thetluid passes to the outlet conduit 7l which is connected to the fronttubulation 59 of row 4d. It is to be realized that in the discussion ofthe heated uid flow circuit of FlG. 8 and the cooled uid flow circuit ofFIG. 9, each interconnection between horizontal rows of the thermopile lis formed by a conduit such as the conduit 67 illustrated in FlG. 5 withthe conduit being secured in a leak-tight manner to the appropriatetubulations 59 along the front and rear surfaces respectively oftheoutward blocks 51.

In order to prevent short circuiting of the electrical ow path,presently to be described, of the thermopile ll, the ow conduits 67desirably are formed from an insulating material such as a nylon tubingwhich may be suitably secured and/or clamped to the appropriate tubulations 59 to prevent leakageat the points of jointure. ln addition, itis to be realized that the particular llow paths illustrated in FIGS. 8and 9 are merely illustrative of llow paths which may be utilized withthe thermopile ll and that other tlow paths may be substituted therefor.For example, the ow paths illustrated in FIGS. 8 and 9 are formed topass through each of the rows of heated and cooled blocks respectivelyin a generally random manner, so that any other random manner ofconnections which accomplishes the same purpose can be substituted. lnorder to obtain the respective thermoelectric heating and cooling of thelluids flowing through the two llow paths in the thermopile ll,anelectrical current must be passed through the thermopile ll. lnfurtherance of this purpose, there are provided a pair of terminals 80and B2 for the thermopile l1 with the positive terminal 80 being mountedon the upper surface of the block 6Ae and secured thereto by suitablemeans to provide good electrical contact between the terminal 80 and theblock 6Ae. Similarly, a negative terminal 82 is mounted on the uppersurface of the block lAe to complete the electrical circuit of thethermopile ll. ln this manner, direct current power is supplied betweenthe terminals Btl and 82 and a current tlow path, to be described,extends through each of the blocks l ofjthe thermopile to form acomplete electrical circuit. The thermopile electrical circuit is formedby a series connection of the terminals 80, blocks 5l, thermoelectricmaterial 53, conductor bridging straps. for example the strap 84 and theterminal 82. In order to provide the desired current tlow path throughthe thermopile ll, insulating means are disposed in a predeterminedmanner between adjacent vertical rows of blocks Sl of the thermopile ll.In this manner the electrical tlow path between adjacent rows of blocksis ,made continuous by means of the bridging conductor straps such as 84without short circuiting .the electrical path. The insulating means maybe formed from-a suitable sheet material such` as the sheets 86 and 8Bwhich are interleaved between adjacent vertical rows of blocks. lfdesired, the sheets 88 may be formed by a plurality of individualsegments of insulating material suchiaa the segment 9l"i|lustrat`ed inthe broken away portion of FIG. 5. The insulating material 86 may beformed from any suitable sheet material, such as a thermoset resinouslaminate, for example a silicone,V phenolic, or melamine aldehyde resinapplied to layersof glass cloth.

The conductor straps 84 are disposed at both the top and bottom surfacesof the thermopile Il and are mounted to bridge alternating vertical rowsof blocks 5l to form a generally sinusoidal current path which passesserially through each of the vertical rows of blocks. More specifically,the vertical rows 6A and 6B are electrically connected by a conductingstrap 84 disposed on the bottom surface thereof and adjacent verticalrows 6B and 6C are connected electrically by a conducting strap 91disposed on the top surface thereof. Similarly, the vertical rods 6D and6E are joined by a conducting strap 94 disposed on the top surface ofthe thermopile 1l. The rows 6E and 6F are electrically connected by aconductor strap 96 disposed on the bottom surface of the thermopile lland the row 6F, being disposed at the back of the thermopile ll is thenjoined to the adjacent vertical row in the next series of rows of blocks5l. More specifically, the row 6F is joined to the row 5F by a bridgingconductor strap 98 disposed on the upper surface of the thermopile ll.The series of rows of blocks 5A, 5B, 5C, 5D, 5E and 5F are similarlyconnected in series by appropriate bridging conductor straps and thelatter series of rows are joined electrically to the series of rows 4Ato 4F by a bridging conductor strap 100 similar in function to the strap98. '111e aforementioned arrangement of joining electrically theadjacent rows of blocks to provide a continuous current flow path forthe thermopile ll is similar ly provided t'or the remaining rows of thethermopile ll until the current llow path reaches the terminal strap 82.

It will be noted that the insulating members 86 and 88 are interleavedbetween adjacent conductor straps such as 90. 94 and 98, to insulateelectrically adjacently disposed conductor straps. ln furtherance ofthis purpose the insulating means 86 and 88 extend between adjacentconductor straps to prevent a short circuiting of the current how pathwhich would eliminate the flow of current through a given row of blocks5l.

ln constructing a thermopile, it is realized that the thermoelectricmaterial 5J must be'selectively disposed between adjacent blocks 5l toprovide the same type of thermal action in each level of blocks 5l, forexample, the blocks 5l at level e are deslrably formed so that thethermoelectric material generates heat at level e. Similarly, at level dthe thermoelectric material S3 provides cooling in all of the blocks atlevel d. ln each of the blocks 5l in levels c and a, the thermoelectricmaterial is formed to provide heating while the blocks 5l at level b,should be subjected to a cooling action. ln achieving the alternatingheating action and cooling action at adjacent levels of blocks Sl, it isto be remembered that as electrical current tlows from n-typethermoelectric material to p-type thermoelectric material a coolingaction is generated between the n-type material and the p-type material.Similarly, as electrical current passes from p-type material to n-typematerial a heating action is generated between the p and ri-typematerial. ln considering electrical current in this manner, it is to berealized that we are considering direct current with the direction ofcurrent llow being the direction of conventional current tlow ratherthan electron ow.

Thu's, to provide respectively a heating action at level e. a coolingaction at level d. a heating action at level c, a cooling action atlevel b and a heating action at level a, it will be realimed thatcurrent llows from the terminal to the block 6Ae and then to the blocks6Ad and Ac, respectively. T hermoelectric material S3 is disposedbetween the conlonting surfaces ot' the blocks 6Ac und Ad as well asbetween blocks Ad and 6Ac. Thus. to achieve thermoelectric cooling inthe block iAd. it will be necessary for the thcrmoelectric material 53between blocks 6Ac and Ad to be of the n-type polarity while thethermoelectric material disposed between bloelor (Md and 6Ac' is p-typematerial. In this manner lhermoelectric heating will be generated inblocks Ae and Ac while tberrnoelectric cooling will be generated inblocks 6Ad.

Thermoelectric material of the alternate types are disposed alternatelyalong the current flow path of the? thermopile 11. Accordingly. in theevent the thermoelcctric material belwcn blocks 6Db and Dc is of thep-type, then the thermoelectric material between both locks 6Dc and 6ndand between blocks Da and 6Db will be n-type material. Similarly,alternate pellets of thermoelectric material at the same level as thethermoelectric material between blocks Dd and 6Dc will also be n-typematerial. More specifically, the thermoelectric material between each ofthe following sets of blocks will be n-type material, be\ tween blocksEc and Eb. blocks SDc and SDb and between blocks De and tiCd. Theaforementioned relative locations of thermoelectric materials ofdifferent polarities exists throughout the thermopile ll.

Referring now to the construction of the internal flow channels 57 ofthe thermopile 1l, it will be noted that it is necessary to insulatecompletely, adjacent blocks Sl of adjacent rows in order to prevent ashort circuiting of the current path through the thermopile l1. inasmuchas each of the blocks 5l is formed from an electrically conductivematerial, it is necessary to maintain the blocks in adjacent rows ininsulating relationship. As heretofore described, sheets of insulation86 are interposed between longitudinal rows of blocks and insulatingsheets 90 are interposed between laterally spaced rows of blocks. Thesheets 90 desirably are segmented so that they may be interleavedbetween the sheets of insulation M.

ln order to provide continuity of how through the flow passages 57,openings 102 are disposed in alignment with the flow passages 57. Toprevent leakage between adjacent bloclts 51 into the space wherein thediscs 90 are disposed, suitable conduit means such as the tubularmembers 104 are interposed between laterally adjacent blocks 90. Thetubular members 104 have the openings thereof disposed in alignment withthe flow passages 57 and are closely received within enlarged ol'fsetportions 104 disposed in adjacent ends of adjacent blocks 51. One meansof sealing the ow passages 51 is illustrated herein as a pair of O-rings106, which are desirably tted in recess formed in the tubular members104. In order to maintain the insulated relationship between adjacentblocks 51 and laterally spaced rows, the tubular members 104 are formedfrom material having a high electrical resistance, for example,

the insulating material forming the insulating members 4 86 and 88. Thetubular members 104 are shown more particularly in FIG. 6. lt will,therefore, be seen that the ow passages 57 continue along an entirelongitudinal row of blocks 51 maintaining the proper insulation betweenadjacent laterally spaced bloclts 5l and resulting in substantially noleakage at the joinders of the blocks 51. ln order to prevent peripheralarcing along the exterior surfaces of the thermopile 11, for example onthe side surfaces and the top and bottom surfaces, respectively, sheetsof insulating material may be suitably disposed on the exterior surfacesof the thermopile 11. For example, insulating sheets are desirablymounted on the opposed side surfaces of the thermopile 11 and insulatingmembers 112 are desirably mounted on the front and rear surfacesrespectively of the thermopile 11. The insulating sheets 112 desirablyinclude a plurality of openings therein disposed to receive each of thetubulations 59 which extend outwardly from the front and rear surfacesrespectively. In addition, similar sheets of insulating material may bemounted on the top and bottom surfaces of the thermopile l1.

Considering now the current flow path through the thermopile ll it willbe secn that the current passes directly from the electricallyconductive block 51 through the thermoelectric pellets 55 to the nextblock 51 along the current llow path. Since the electrical resistancealong the entire cross section of a given block 51 is substantially ofthc same magnitude, thc current will be diffused substantially equallyacross the block 51, utilizing all of tlte thcrmoelecttic materialdisposed adjacent the block.

lt will be seen that cooling is generated by the thermoelectric materialin one direction and heating is generated by the thetmoelectic materialin the opposite direction. Accordingly, the heat flow path for thegenerated heating and cooling passes directly from the thermoelectricmaterial 53 to the adjacent flow conduits 51 disposed on opposite sidesof the lhermoelectric material 53. Since the blocks S1 are formed from aheat conductive material, it will be seen that the blocks S1 arerespectively heated and cooled by the thermal changes caused by thethermoelectric material. The fluid llowing through the respective heatedfluid and cooled uid flow paths of the thermopile 1l passes in heatexchange relationship with the adjacent blocks 51 and is respectivelyheated or cooled by the blocks 51 in the flow path. lt will be realizedthat there is provided no electrical insulation in the heat flow pathfrom the thermoelectric material 53 to the flow channels 57. The heattiow path of the thermoelectric device is parallel to the electricalflow path of the device. As such, the removal of insulation from theheat flow path through the thermopile 11 constitutes a substantialincrease in the efliciency of the thermopile 1l resulting in the use ofa substantially small quantity of thermoelectric material 53 to obtain apredetermined amount of thermoelectric heating or cooling. Furthermorelthe apparatus illustrated herein which achieves direct transferthermoelectric heating and cooling is of a compact configurationrequiring very little space so that the same is usable in applicationswherein substantial space for cooling or heating equipment is notavailable.

lt will be appreciated that for direct transfer thermoelectricapparatus, a power supply producing high currents at low voltagesdesirably is utilized. More specifically, the electrical resistancealong the heat flow path is minimized so that a power supply whichgenerates 9V: volts will produce 750 ampcres of current through thethermopile 1l.

ln FIG. 7, a direct transfer thermoelectric apparatus is illustrated andis suitable for use in applications wherein very large thermoelectricheating or cooling requirements exist. More specifically, instead ofdividing the various levels of blocks 51 of FIG. 5 into a plurality ofinsulated groups, there is merely substituted a large block of a heatconductive material having flow conduits formed therein for each groupof blocks Sl in FlG. 5 fonning a given level, ln accordance with FIG. 7,a plurality of blocks 122 are mounted in tandem to form the thermopile120. Each of the blocks 122 desirably is formed from material havinggood heat transfer and electrical conductivity properties, such ascopper or aluminum. Each block 122 is provided at its ends with aplurality of outwardly extending tubulations 124 and a plurality of llowpassages 126 are formed in each block 122 intermediate juxtaposedtubulations 124, respectively. More specifically, each of the flowpassages 126 passes from the tabulation 124 on the front surface 128 ofthe thermopile 120 through the block 122 and is connected to thetubulation 124 disposed at the rear surface 130 of the thermopile 120.The flow passages 126 correspond to the flow passages 56 of FIG. 5 withthe exception that the ow passage is formed entirely in a single block122. There is disposed between adjacent blocks 122 and the thermopile120 a plurality of pellets of therrnoclectric material 130. The pellets130 desirably cover the entire juxtaposed surfaces between adjacentblocks 122. The layers of therrnoelectric material 130 desirablyalternate so that the uppel layer` comprises, for example, an n-typematerial, the adjacent layer a p-type material. the third layer ann-type material and the lowest layer a p-typc material.

It will, therefore, be seen that the thermopile 120 of FIG. 7 comprisesa thermopile of generally the .same type as that illustrated in l'l(i.5, but has u once-through electrical path. 1n this instance, however,thc current merely passes directly through the entire surface of each ofthe blocks 122 rather than by means of the circuitous path of FIG. 5. Inaddition, it will'be seen that a plurality of ow openings are formed ineach of the blocks 122 rather than a single ow opening inthe blocks'Slof FIG. S. The thermoelectric function of the thermopile 120 is exactlythe same as that of the thermopile 11 of FIG. so that each of the blocks122 comprises a portion of the heated fluid tlow circuit or the cooleduid ow circuit respectively. More particularly, the upper block 122rather than a single flow opening in the blocks 51 successive blocks arealternately Vcooled and heated respectively, to provide layers whichcorrespond thermodynamically to alternating heat source portions andheat sink portions. Each of the tubular passages 126 are connected inseries in anysuitable mannerauch as a connection similar to thatillustrated in FIGS. 8 and 9 so that cooled tluid passes through each ofthe passages 126 in the cooled block 120 and heated huid passes througheach of the passages 126 in the heated blocks 122. In order toaccomplish the once-through electrical tlow path a pair of electricalterminals are respectively mounted on the upper and lower blocks 122respectively. The upper or positive electrical terminal 132 is desirablyformed to engage the entire upward surface of the upper block 122 andthe `lower or negativeelectrical terminal 134 is also formed to bedisposed in intimate contact with the entire lower surface of the lowestvblock 122. In this manner, electrical current tlowing from the upperterminal 132 to the lower terminal 134 is diffused and passes throughthe entire cross section of each of the blocks 122 and thermoelectriclayers. In other words, the current density through the thermopile 122is substantially equal per unit area. This equal current density isachieved by the fact that the resistance of the thermopile 120 issubstantially equal per unit area.

In order to prevent arcing along the side walls of the thermopile 120,insulation means such as insulation sheets 136 and 138, formed. from thesame material as the insulation 110 of FIG. 5. are mountedgon the twoside walls of the thermopile 12., and simila insulation sheets 140 and142 are mounted respectively on the front and rear side walls ofthevthcrmopile 120.V The insulating sheets 140 and 142 desirably areprovided with a plurality of openings therein to receive thetribulations 124 of the blocks 122 respectively.

Accordingly, in insulations wherein substantial cooling tonnage isutilized, a unit of the type illustrated in FIG. 7 can besubstituted forthe thermopile arrangement illustrated in FIG. S so that insulatingconnectors auch as the tubular members 104 need not be provided betweenadjacent bloclrs. The' arrangement oflFlG. 7, however, stili results ina direct transfer thermopile arrangement wherein there is disposed noelectrical insulation in the heat new path of the thermopile 120. Inother words', heating and cooling respectively pass from thethermoelectric pellet layers 13010 the appropriate blocks 122 and to thelluid passing through the flow passages 124 without encountering anyelectrical or heating insulation in the heat flow path.

This aspect of this invention permits the use of substantially smallerquantities of thennoelectric material having substantially smallerpellet lengths so that the heat pump approaches the quantitieslillustrated in FIG. 3, rather than the relatively smaller quantitiesillustrated in FIG. 1 for pellet length of increased dimensions.

with reference to the arrangement of FIG. I0. itwill be appreciated thatthe FIG. l0 embodiment is similar to the apparatus of FIG. 5.Accordingly like parts will be designated by the same referencecharacters and will not be described again.

In FIG. l0, the sheet insulating materials B6, 90 and 112 of FIG. S hasbeen removed and there has been substituted in their stead an insulatingmaterial 150 desirably formed from a moulded resinous powder. Severalthermosct, moulded resinous materials such as phenolic resins, urearesins, melamine resins and appropriate lilter materials auch as silicaor asbestos, may be used for the insulating vmeans 150. In accordancewith this embodiment, the insulating means is placed in all voidsbetween modules S1, after the thermopile has been otherwise assembled.The insulation 150 initially is in a powder or powder-liquid suspensionso that the same flows into all void spaces. The suspension is thenthermally treated, with or without impressive forces exerted thereon,until the same solidilies to form an integral unitary mass. With thisarrangement, the use of the several layers or sheets of insulatingmaterial 86 and 9| of FIG. 5 need not be individually positioned andassembled.

It is to he realized that it is only by virtue of the direct transferaspects of the thermopile constructions of this invention thatsubstantially higher heat pumping rates can be achieved forsubstantially smaller pellet lengths. Aa a result, decreased quantitiesof thermoelectric materials per ton of heating or cooling can beutilized. Referring more specifically to the family of curvesillustrated in FIG. 2, the use of a direct transfer thermoelectricdevice permits the operating points for the thermopile to range in thefamily of curves 56, 58, 60, 62, 64 and 66, rather than the curves 50and 52 of FIG. 2, wherein the heat pumping rates per pound ofthermoelectric material is substantiallly smaller.

In accordance with the invention the thermopile illustrated herein canserve as an ellicient electrical current producing device. ln thisregard, there is provided for the thermopile 11 of FIG. l. a source ofrelatively high temperature tluid which hows through the thermopile l1by the now circuit formed by the conduits. 63 and 65. The llow circuitformed by conduits 69 and 71 is connected to a source of relatively lowtemperature uid, resulting in the creation of a temperature dili'crenceacross each of the thermoelectrir.: pellets 53. The thermoelectricpellets then act in reverse and produce an electrical potential in thethermopile 11, which potential is imposed across the terminals $0 and82. The performance of the thermopile 11 as an electric generatorprovides the same advantages and etliciencics as those brought outherein in connection with the performance of the thermopile 11 as atemperature varying device.

It will be realized that when the thermopile l1 acts as an electricgenerator, the output voltage of the generator is dependent directlyupon the temperature difference across the pellet (At). Accordingly thetemperature difference across the pellet is desirably maintained aslarge as possible.

For an electrical generator, the equation governing the Y pellettemperature diterent (Atp) is:

safer-Auen., (6)

where the quantities At, A", and an, are the same quantities describedabove in connection with Equation 4.

To provide a large value for At,.Y it will be appreciated that thequantities At", and tat,c must he maintained as small as possible. Inaccordance with this invention, the quantities AtfhAtn, are very smallin magnitude because there is provided no electrical insulation in theheat llow path. As a result, the use of good heat transfer materialbetween the junctions of the thermoelectrc pellets 53 and the adjacentheat sources and heat sinks formed by the adjacent ilow passages 57provides a construction where in the condition described by Equation Sis very nearly reached.

It will be appreciated that many modifications in the apparatusspecifically -shown and described herein may be made without departingfrom the broad spirit and scope of this invention. Accordingly, it isspecifically intended that the thermopile arrangement shown anddescribed herein be interpreted as illustrative of this invention ratherthan as limitative thereof.

Wc claim as our invention: i

l. ln a thermoelcctric temperature varying device, a plurality of spacedlayers of thermoelectric material, a plurality of electricallyconducting members each having a straight through closed liquidpassageway formed therein, each of said members having generally opposedsides secured respectively to adjacent ones of said layers to bridgesaid adjacent ones of said layers, circuit means forming a seriesconnected electrical current tlow path through said members and saidlayers, terminal means coupled to the extremities ot said current tlowpath, said straight through huid passageways forming a pair ot'independent tluidpassages each extending between said layers for lluidsto be respectively heated and cooled therein, and adjacent ones of saidpassageways being disposed in insulated relationship to prevent the owof current directly between said adjacent ones of said passageway means.

2..ln a thermoelectric temperature varying device, a plurality of modulestages, each of said stages comprising a block member formed ofelectrically conducting material with each block member having a pair ofopposed surfaces, a layer of thermoelectric material mounted on each ofsaid opposed surfaces, each of said block members having a straightthrough liquid passageway means extending therethrough between undgenerally parallel to said opposed surfaces thereof, conduit meansconnecting said liquid passageway means in series, and said conduitmeans being formed to resist the Bow of electrical current therethrough.

3. In a thermoelectric temperature varying device, a plurality of modulestages, each of said stages comprising a block member formed ofelectrically conducting material with each block member having a pair ofopposed surfaces. a layer of thermoelectric material mounted on each,ofsaid opposed surfaces, each of said block members forming a straightthrough tluid passageway means therethrough extending between saidsurfaces, conduit means connecting each of said straight through tluidpassageway means in series, and said conduit means being formed toresist the dow of electrical current therethrough, said passageway meanscomprising openings formed in said block members, said conduit meansextending in part into said openings, and lluid sealing means interposedbetween juxtaposed portions of said openings and said conduit means.

4. ln a thermoelectric temperature varying device, a plurality of modulestages, each of said stages comprising a block member formed ofelectrically conducting material with each block member having a pair ofopposed surfaces, a layer of thermoelectric material mounted on each ofsaid opposed surfaces, each of said block members forming straightthrough tluid passageway means therethrough extending between saidsurfaces, conduit means connecting each of said huid passageway means inseries, and said conduit means being formed to resist the ow ofelectrical current therethrough, heat exchange means of electricallyconducting material connected in bridging relationship acrosspreselected adjacent stages, said heat exchange means being secured toone of said layers of one of said adjacent stages and to one of saidlayers of the other of said adjacent stages to form a series currenttlow path through said one stage and through said other stage.

S. ln a thermoelectric temperature varying device. conduit means forminga lluid tlow path.l said ooriduit means including a plurality ot spacedelectricallyconducting blocks having at least one straight throughopening extending between opposed sides thereof ,and `a plurality ofstraight through passageway meansformed to `resist thc Ilow ofelectrical current therealongserially connecting the openings ofadjacent ones -ot' said blocks, each of the blocks havinga pairwofgcorretiponding spaced surfaces thereon extending generally parallelto said opening, a layer of thermoelectric material mounted on each ofsaid spaced surfaces, electrically conductive means mounted in bridgingrelationship `from one of said thermoelectric layers of one of saidblocks to the corresponding thermoelectrlc layenoi another otsaidblocks, and said electrically conductive means having heat exchangenieant mountedthereon.

6. In a thermoelectric device, a module member of electricallyconducting material having a pair of opposed surfaces, said modulemember having a layer of thermoelectric material mounted on each ot'said opposed surfaces, said module having astraight through conduitformed therein extending between said opposed surfaces generallyparallel thereto tor conducting a heat exchange tluid therethrough, andterminal means coupled to each of said layers of thermoelectric materialforming an electrical current tlow path whichfextends in series betweensaidlayers and said module member.

1. ln a thermoelectric temperature varying device, the arrangementcomprising a 4plurality of groups of at least three tandemly mountedheat exchange modules, whereby each of said groups includes a modulelocated at a lower level, at an intermediate level and at an upperlevel; each of the corresponding ones of said modules in each of saidgroups located at said lower level having a straight through openingformed therein; electrically resistant passageway means connecting saidlast mentioned openings in series; each of said modules located at saidintermediate level having straight through ,openings formed therein;electrically resistant conduit means connecting said last mentionedopenings in series; e ch of said modules at said upper level havingstraight t rough openings formed therein; electrically resistant tlowpath means connecting said last mentioned openings in series, wherebysaid passageway means, said conduit means and said ow path meanscooperate to form three separate tlow circuits formed respectively atsaid lower, said intermediate and said upper levels; thermoelectricmeans disposed intermediate adjacent modules in 4each ot' said groups;conductor means disposed in bridging relationship across adjacent onesof said groups to connect each of said groups in electrical series;terminal means formed on predetermined ones of `said modules forsupplying electrical current through each of said modules in a serieselectrical flow path; said thermoelectrc means being polarized toproduce thermoelectric heating of the ones of said modules in saidgroups located at said intermediate level; said thermoelectric meansalso being polarized to produce thermoelectric cooling in the ones ofsaid modules of each of said groups located at said lower and said upperlevels; means supplying a heat exchange iluid to each of said owcircuits, whereby said heat exchange lluid flowing through the one ofsaid llow circuits at the intermediate level is heated and the heatexchange uids flowing through the ones of said flow circuits located atsaid upper and lower levels are cooled.

8. ln a thermoelectric temperature varying device, the the arrangementcomprising a first group of tandemly mounted heat exchange modules, alayer of thermoelectric material disposed between and engaging adjacentopposed surfaces of adjacent ones of said modules with adjacent ones ofsaid layers being thermoelectrically dissimilar, a second group oftandemly mounted heut exchange modules mounted coextensively with andadjacent said first module group, a layer of thermoelectric materialdisposed between and engaging adjacent surfaces of adjacent ones of saidmodules of said second group with adjacent ones of saidlayers beingthermoelectrically dissimilar, the curresponding ones ot said layers ofsaid. lirst and second groups being formed from thermoelectricallydissimilar material, a conductor electrically connecting thecorresponding end modules of said first and second groups to form a,series electrical llow path `through said modules of slid lirst andsecond groups, molded electrical insulating material disposed insubstantially all voids between said first and second module groups,tluid llow path means 17 formed directly in each of said modules andextending between said opposed surfaces thereof, and electricallyinsulated conduit means connecting said tlow path means of thecorresponding modules of said first and second groups respectively.

9. In a thermoelectric temperature varying device, a plurality oftandemly mounted electrically conducting heat exchange modules, a layerof thermoelectric material disposed between juxtaposed surfaces ofadjacent ones of said modules, with adjacent ones of said layers beingthermoelectrically dissimilar to respectively heat and cool alternatingones of said modules, each of said modules having a plurality of fluidflow openings formed therein extending between said surfaces thereof andsubstantially parallel to said layers, means for connecting said modulesto a source of electrical power to cause current to flow through saidmodules and said layers.

10. In a thermoelectric temperature varying device, at least threetandemly mounted electrically conducting heat exchange modules, a layerof thermoelectric material disposed between juxtaposed surfaces ofadjacent ones of said modules, with adjacent ones of said layers beingthermoelectrically dissimilar to respectively heat and cool alternatingones of said modules, each of said modules having a plurality of uidtiow openings formed therein extending between said surfaces andsubstantially parallel to said layers, means for connecting said modulesto a source of electrical power to cause current to tlow through saidmodules and said layers, means for connecting each of said openings ofsaid cooled modules in series to form a cooled uid flow path, and meansfor connecting the remaining ones of said openings in series to form aheated Huid tiow path.

Il. A thermoelectric heat pump assembly comprising a plurality of bodiesof P and N type semi-conductor ma terial, hot and cold junction bridgessecured to said bodies and bridging between the ends of the same to formhot and cold junctions, said hot junction bridges in the form of firsttube sections, said cold junction bridges in the form of second tubesections, .raid first and second tube sections having their axesperpendicular to the current direction in said bodies, groups oj saidrespectiva hrst and second tube sections being iongitudilullly joined byelectrically nonconductive ring elements to form fluid-tight continuousconduits.

I2. A thermoelectric heat pump assembly as in claim II wherein saidfirst and second tube sections have their axes parallel to each other toform parallel continuous pipe assemblies ol respectively hot and coldjunctions in a two-dimensional array.

I3. A thermoelectric heat pump assembly comprising a plurality of bodiesof P and N type semiconductor material, hot and cold junction bridgessecured to said bodies and bridging between the ends of the same to formhot and cold junctions, said hat junction bridges in the form of firsttube sections, said cold junction bridges in the form of second tubesections, groups of said respective rst and second tube sections beinglongitudinally joined by electrically nonconductive ring elements tolorrn fluidtight continuous conduits.

i4. A thermoelectric heat pump assembly as in claim I3 wherein said )rstand second tube sections` have their axes parallel to each Other to formparallel continuous pipe assemblies of respectively hot and coldjunctions in a two-dimensional army.

References Cited The following references, cited by the Examiner, are ofrecord in the patented file of this patent or the original patent.

UNITED STATES PATENTS 2,729,949 l/ 6 Lindenblad 62-3 X 2,837,899 6/ 1958Lindenblad 62--3 2,870,610 1/ i959 Lndenblad 62-3 2,884,762 S |959Lindenblad 62--3 3,006,979 10/ 1961 Rich 62-3 3,054,840 9/ 1962 Alsing62--3 3,111,813 11/ 1963 Blumentritt 62--3 WILLIAM I. WYE, PrimaryExaminer

